The present invention relates to a video signal processing apparatus and a video signal processing method. More particularly, the present invention relates to a video signal processing apparatus and a video signal processing method which are capable of outputting a display having a high picture quality by effectively utilizing an output resolution.
In recent years, as a signal format of a video signal in broadcasting, a 525i (interlace), 525p (progressive), 1125i or 750p signal formats have been used. As a video signal output terminal for outputting the video signal from a digital video apparatus to a video signal input apparatus, a D terminal prescribed by the CP-4120 of the EIAJ (Electronic Industries Association of Japan) has been used. Examples of the digital video apparatus are a set top box (STB), a satellite tuner, a DVD (Digital Versatile Disk) apparatus and a Blu-ray disk recorder, whereas an example of the video signal input apparatus is a display apparatus.
This D terminal includes a D1 terminal for a video signal having the 535i signal format, a D2 terminal for a video signal having the 525i or 525p signal format, a D3 terminal for a video signal having the 525i, 525p or 1125i signal format and a D4 terminal for a video signal having the 525i, 525p; 1125i or 750p signal format. In each of the digital video apparatus, on the basis of the input signal format and the output setting of the D terminal, specifications of the signal format of an output video signal are determined in advance. The output setting of the D terminal is referred to hereafter as the output format setting and the signal format of an output video signal is referred to as the output format.
FIG. 1 is a diagram showing typical specifications of the D1 terminal generally used. In the typical specifications shown in FIG. 1, if the output format setting is the D1 terminal, an input video signal of any signal format is output in the 525i signal format. If the output format setting is the D2 terminal, an input video signal of the 525i signal format is output in the 525i signal format, whereas an input video signal of the 525p, 1125i or 750p signal format is output in the 525p signal format.
If the output format setting is the D3 terminal, an input video signal of the 525i signal format is output in the 525i signal format, and an input video signal of the 525p signal format is output in the 525p signal format, whereas an input video signal of the 1125i or 750p signal format is output in the 1125i signal format. If the output format setting is the D4 terminal, an input video signal of the 525i signal format is output in the 525i signal format, an input video signal of the 525p signal format is output in the 525p signal format, and an input video signal of the 1125i signal format is output in the 1125i signal format, whereas an input video signal of the 750p signal format is output in the 750p signal format.
As described above, for each of the D terminals employed in the conventional digital video apparatus like the one described above, the output signal format of the video signal is set on the basis of the input signal format of the video signal. Thus, in some cases, the output signal format of the video signal may be changed to accompany a change made to the input signal format of the video signal.
With the output format setting set at a setting for the D4 terminal, for example, assume that after a broadcast content of a 750p video signal, a broadcast content of a 525p video signal is received. In this case, the output signal format of the video signal is changed from 750p to 525p. That is to say, since the output signal format of the video signal is changed from 750p to 525p, the synchronization of the digital video apparatus goes wrong. Thus, the signal format change raises a problem that a screen appearing on a display apparatus connected to the digital video apparatus through the D terminal changes temporarily irrespective of the user's intention.
A digital video apparatus may have a video signal output terminal outputting all signal formats of a video signal at a fixed 1125i signal format, as shown in FIG. 2. That is to say, an input video signal with any format is output at the 1125i signal format at this video signal output terminal so that the digital video apparatus can output only a video signal with the 1125i signal format. Thus, this configuration raises a problem of being incapable of outputting a video signal with another format even if the other format is desired.
In addition, a D terminal employed in the conventional digital video apparatus may not necessarily output a video signal with a signal format of a maximum resolution for the D terminal. For example, assume a digital video apparatus has a D4 terminal and is capable of outputting a high resolution video signal at the 750p signal format as shown in FIG. 1. Even in this case, the digital video apparatus has a problem that the highest resolution 750p signal format of the D4 terminal cannot be utilized effectively for an input video signal with the 525p signal format because the video signal is output by lowering the resolution to a value for the 525p input signal format of the video signal.